DE-OS 3 529 984 (LeA 24 047) describes the reaction of 5 diols with polycarbonates to form diphenol carbonates of diols, the diols having a molecular weight Mn of from 300 to 15,000. JA 69-11377 describes the etherification of OH end groups of polyethyleneglycol by a treatment with diphenylcarbonate. DE-OS 2 619 831 (LeA 16 933) describes the preparation of carbonic acid aryl esters of polyalkylene oxide polyols. None of these literature references provides any suggestion for the process according to the invention.